Test equipment for network analysis must now operate at a wide band of frequencies above 100 GHz. Purely electrical components that are to operate in this frequency range present significant challenges. As a result, systems in which part of the processing is performed in the optical domain have been developed. For example, an amplifier for amplifying a signal in a band of frequencies from 30 to 300 GHz is difficult to implement in conventional electrical components. However, if the signal is used to modulate a light signal, the range of optical frequencies that must be amplified is very narrow, and hence, the signal can be amplified by amplifying the optical signal using conventional optical amplifiers and then the signal can be recovered by demodulating the amplified optical signal.
Test equipment that utilizes optical processing has been developed to address the challenges of working over a broad band of frequencies in the 100 GHz range. For example, a co-pending patent application, PCT/US2014/021788, filed Mar. 7, 2014, describes a network analyzer that requires a light signal modulated in this frequency range and the RF signal used to modulate that signal. Providing compact probes that generate the modulated light signal and also provide RF for coupling to a device under test (DUT) pose significant challenges.